Recognizing fleeting facial expressions with different viewpoints

Most research of facial expression recognition used static, front view and long-lasting stimuli of expressions. A paucity of research exists concerning recognition of the fleeting expressions from different viewpoints. To investigate how duration and viewpoints together influence the expression recognition, we employed expressions with two different viewpoints (three-quarters and profile views) and showed them to the participants transiently. The duration of expressions was one of the following: 20, 40, 80, 120, 160, 200, 240, or 280 ms. In experiment 1, we used static facial expressions; In experiment 2, we added dynamic information by adding two neutral expressions before and after the emotional expressions. The results showed an interaction effect between viewpoint and duration on expression recognition. Furthermore, we found that happiness is the easiest expression to recognize even under the conditions of fleeting presentation and side-view. This study informed the automatic expression recognition of human data under conditions of short duration and different viewpoints.